o3one, is a VMS-like hobby operating system with some UNIX features currently in development. It includes VMS version control in the filesystem dfs, as well as both stream and "mailbox" style pipes. Development is currently headed towards an Alpha port, and a GUI is in development.

OpenVMS has some nice features that Linux does not (yet) have. What comes to mind is

1. The resource locking service (sys$enq). It has been ported by IBM to Linux under the name DLM (Distributed Lock Manager) but is not yet included in the official kernel.
2. The commandline interpreter (DCL). It's extensive and well structured as the rest of OpenVMS. Bash is a mess in comparison - at least at first glance.
3. Structured return/exit code handling. Programs on OpenVMS do not return 0, 1 or -1 or something as in Linux but rather a symbolic code that indicates who, what, how bad. With a nice stack dump on the spot if desired. OpenVMS has no concept of a core file as in Linux.

The closests equivalent in Linux to logical names are symlinks. Environment vars are in OpenVMS called symbols. ASTs are what Windows call APCs and what is setup using sigaction() in Linux. Event flags are what are signals in Linux.

Coming from OpenVMS I've gotten used to Linux, even started to appreciate some of its features and I'm not sure that what is needed now is yet another OS. I think the focus should be on improving Linux with the best parts from other OSes.

Have to agree and disagree with Claus:
1) Cluster Resource locking is great. My server uses native VMS filesystem across nodes for data access (DB like) and synch-ing.
2) I personally dislike DCL. I find it cumbersome and non-intuitive.
3) As a developer, numeric exit code is preferable for a number of reasons (portability first). But core-dump on VMS is really good. It takes x10 times less time to get the point of crash from customer site with VMS than Tru64.

More Likes:
1) Clustering. Simply the best.
2) Reliability. Not a single reboot for 2 years on development cluster.